This invention relates to a holder for supporting a test strip used to measure the intensity of shot peening so that the intensity of shot peening in internal cavities may be controlled.
Shot peening is commonly used to work harden critical components. When a component is shot peened, the component is exposed to a stream of shot which impacts upon the component. However, the intensity of shot peening must be carefully controlled, because peening at intensities both above and below a critical range will not harden the component properly. Accordingly, a procedure has been developed to measure the intensity of peening. Commonly, a test strip of known dimensions is mounted on a holder, the peening apparatus is set up in the same manner as it will be used to peen the component, and a stream of shot is directed against the test strip for a predetermined time period. The test strip is then removed from the holder, at which time the test strip relaxes into a natural curvature, the magnitude of which is measured by an appropriate gage, such as the gage disclosed in U.S. Pat. No. 5,297,418. If the measured deflection of the test strip indicates peening intensity within the desired range, peening of the component may be initiated. If the measured deflection is outside of the desired range, the equipment is adjusted, a new test strip is installed in the holder, and the process is repeated.
The foregoing process for measuring the intensity of the peening process works well for surface peening. However, critical components often include internal bores, slots, grooves and similar internal cavities, often having a complex shape, which must be peened. The above intensity measurement process does not yield accurate readings for such internal cavities, since the shot is concentrated in a small volume and ricochets off of the walls of the cavity, thus making measurement of the peening intensity by common methods difficult and inaccurate.
The present invention provides a relatively accurate measurement of the intensity of shot peening of internal cavities. A conventional test strip is mounted in a holder which includes a receptacle receiving any of multiple inserts configured to form a segment of an internal cavity of a component to be peened. The test strip defines the remainder of the cavity. The shot stream to be measured is introduce into the cavity, after which the test strip is removed and measured in the conventional manner. Accordingly, the intensity of peening in internal cavities may be measured with relative accuracy. By providing multiple inserts, intensity of peening in cavities of varying sizes may be measured by simply changing the insert.